ESA hopes to launch Rosetta late February

http://sci.esa.int/science-e/www/obj...objectid=34614

One of the goals is a soft landing on comet 67P Churyumov-Gerasimenko.

In my opinion this will be a great milestone for space exploration. Near
Earth Object resources could be helpful for human colonization of the
solar system. I hope this NEO soft-landing (in about ten and a half
years) will be the first of many.

This interesting comet is a recent immigrant into the inner solar
system. From an ESA page:


"The comet has a particularly unusual history. Up to 1840 its perihelion
distance was 4.0 AU (four Sun-Earth distances or about 600 million km)
and the comet was completely unobservable from Earth. That year, a
fairly close encounter with Jupiter caused the orbit to move inwards to
a perihelion distance of 3.0 AU (450 million km). Over the next century,
the perihelion gradually decreased further to 2.77 AU. Then, in 1959, a
further Jupiter encounter reduced the perihelion to just 1.29 AU. It
currently completes one orbit of the Sun every 6.57 years."


This paragraph surprised me. I had been under the impression that orbits
such as this were chaotic (that is a very small change can lead to a
very different orbit later on) and it was hard to extrapolate a comet's
path past several encounters.

--
Hop David
http://clowder.net/hop/index.html

In article ,
Hop David wrote:
"The comet has a particularly unusual history..."

This paragraph surprised me. I had been under the impression that orbits
such as this were chaotic (that is a very small change can lead to a
very different orbit later on) and it was hard to extrapolate a comet's
path past several encounters.

Generally speaking, yes. But in this case there are only two main
encounters involved. Since the comet was discovered in 1969, the 1959
encounter should be fairly solidly known, and it's not too much of a
stretch to go back one more to 1840.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |